In general, anesthesia systems comprise various equipment necessary to anesthetize a patient and maintain the patient in an anesthetized state until a particular medical procedure is completed. Such systems typically include pressure regulators, flow control devices, gas mixing devices, and vaporizers to vaporize a volatile liquid anesthetic and to introduce the anesthetic laden gases into the patient. The patient is usually connected to the system by means of a facemask or other device. The facemask interfaces with the anesthesia system via a patient circuit that typically has an inspiratory limb through which the gases are introduced into the patient and an expiratory limb that conveys the exhaled gases from the patient. Such limbs may be separate conduits joined by a wye piece at or near the patient or may comprise coaxial conduits commonly known as Bain circuits.
In a typical anesthesia system, the overall flow of gases to and from the patient may be in a generally closed circuit. That is, the patient is connected to a substantially closed loop supply of gasses and re-breathes certain of those exhaled gases supplemented by fresh gas. Alternatively, the patient circuit could be an open circuit and all of the exhaled gases simply vented or channeled from the system to an external environment and not re-breathed by the patient. Other variety of circuits are used that deliver the anesthetic gases to the patient, such as semi-open circuits and the like.
As the driving force to the patient, a ventilator is used and which basically breathes for the patient since the patient is under anesthesia and is unable to carry out the normal spontaneous breathing functions. The ventilator, therefore, provides a quantity of the gas containing a metered quantity of the anesthetic agent along with other gases such as N2O and, of course, a life sustaining percentage of oxygen.
Gas containing the anesthetic may be delivered directly by the ventilator into the patient circuit for introduction to the patient or may include an intermediate mechanism such as a bellows. In the latter case, the gas from the ventilator does not contain the anesthetic agent but is used to simply power the bellows by collapsing the bellows to deliver the anesthetic containing gas from the bellows to the patient. With the use of a bellows, the patient is basically isolated from the ventilator and it is possible to use the bellows to allow re-breathing of the patient's exhaled gases to conserve those gases, including the anesthetic agent.
A patient can also be manually ventilated by means of a flexible container or “bag” provided on the ventilator. The bag is filled with breathing gases and manually squeezed by a clinician to provide breathing gases to the patient. Use of the bag or “bagging the patient” is often required or preferred by clinicians as it enables the clinician to physically control the delivery of breathing gases to the patient. Patients are often bagged during surgical procedures when anesthesia is induced in the patient by entraining the anesthetic in the breathing gases. Another environment in which patients are often bagged is in an intensive care unit.
Ventilators typically have two cycles, an inhalation cycle where gas is being forced into the patient and an exhalation cycle where the ventilator allows the patient to exhale through an exhalation valve that vents some of the exhaled gases from the system. The ventilator, therefore, controls both the patient's inhalation and exhalation and the overall circuit is fairly restricted with respect to gases from the overall system being vented to the surrounding ambient.
Another typical function of such anesthesia systems is an oxygen flush that is manually operated by the user to provide an instant flush of oxygen into the patient breathing circuit. The oxygen flush is commonly used to recharge the bellows in the case of a leak in the patient circuit or to rapidly purge the patient circuit of anesthetic gases in the event of an overdose of the anesthetic agent. The latter function is carried out whether or not there is a bellows being used in the anesthesia system and may be used where the anesthetic gases are supplied directly to the patient circuit from the ventilator. Generally, a manual valve is pushed by the user to activate the oxygen flush and the button, when released, stops the flush. When activated, the excess oxygen from the flush stream of oxygen is released by means of a popoff valve in the anesthetic circuit.
During manual ventilator or “bagging”, the caregiver is often required to compress the bag with one or both hands, adjust pressure valves associated with the anesthesia system, press or turn a valve to operate the oxygen flush and keep the circuit full of gas, and in some cases hold a mask on the patient's face. These activities are time consuming and require the caregiver to devote both hands to the above-described manual operation. Also, if bagging is carried out for a long time, it becomes fatiguing to the caregiver, lessening both the fineness of the control of breathing gas supply and the sensing of lung or other respiratory conditions affecting the subject. The bag is usually positioned along the patient circuit, which restricts the degree to which the caregiver, when bagging a patient, can move about the patient, for example, to observe a surgical patient positioned in a manner appropriate to the surgery to be performed. The same is true when the pneumatic elements of the ventilator, rather than the bag, are providing the breathing gases to the patient since the controls necessary to operate the pneumatic elements are placed at a fixed location on the ventilator.
If a leak occurs in the breathing circuit, for example between the facemask and the patient, it is usually necessary to operate the oxygen flush to recharge the bellows, as described above. Such an event currently requires the caregiver to manually operate a flush valve or press and hold down a button on the ventilator to actuate the valve. This can be time consuming and typically requires the caregiver to interrupt other caregiving activity.
As such, it is desirable to provide a method and arrangement that enables a caregiver to control medical apparatus, such as an anesthesia machine and ventilator, without the need for direct manual interaction. Such an arrangement would allow the caregiver to perform other tasks during treatment of the patient.